1. Field of the Invention
This invention relates to an engine lubricating system and has particular applicability to a fuel injected two cycle engine.
2. Description of the Related Art
Two cycle internal combustion engines are typically lubricated by supplying lubricant through the engine""s induction and porting system for lubricating the various moving components of the engine. Lubricant can be supplied in a wide variety of manners. For example; lubricant may be mixed with fuel, may be sprayed into the induction system of the engine, may be delivered directly to certain components of the engine, or may be supplied by any combination of the above.
In conventional two cycle engines, air from an air intake system travels through reed valves into a crankcase chamber of the engine. Air from the crankcase chamber is supplied to the cylinders for combustion. Typically, fuel such as gasoline is mixed with lubrication oil and supplied to the air flow on an upstream side of the reed valves. The viscosity of this fuel/lubricant mixture is low in comparison with a typical lubricant alone. Because of its low viscosity, the mixture is easily sprayed and distributed to various parts of the engine for lubrication.
In order to reduce unburned hydrocarbons and engine exhaust emissions, many internal combustion engines now employ direct fuel injection, wherein the fuel is directly injected into the cylinders. In these engine arrangements, the fuel is not mixed with lubricant. As a result, the viscosity of the lubricant is increased and the lubricant is not smoothly sprayed and distributed. Due to its high viscosity, lubricant particles tend to stick together during distribution. Inconsistent lubrication of various engine components can occur at an increased frequency, possibly preventing even distribution of lubricant over the engine components. Adequate lubricant distribution is desired to protect engine components, especially during the break-in period. Excessive lubrication, however, may cause drawbacks such as increased lubricant consumption and possible decreased engine performance.
Accordingly, there is a need in the art for a two-cycle, fuel-injected engine lubrication system which promotes consistent and thorough distribution of lubricant to moving components of the engine, assures adequate lubrication during break-in of the engine, and provides a volume of lubricant adapted to promote lubricant effectiveness and minimize lubricant consumption.
In accordance with one aspect, the present invention includes an internal combustion engine comprising a first cylinder formed in a first cylinder bank and a second cylinder formed in a second cylinder bank. The cylinder banks are oriented in a V-shaped formation with the first cylinder bank being generally on a first side of the engine and the second cylinder bank being generally on a second side of the engine. A crankcase encloses at least a portion of a crankshaft therein. The crankshaft is adapted to rotate in a manner creating a swirling flow of air within the crankcase, which is divided into at least a first crankcase chamber communicating with the first cylinder and a second crankcase chamber communicating with the second cylinder. A first lubricant insertion port opens into the first crankcase chamber from the second side of the engine, and a second lubricant insertion port opens into the second crankcase chamber from the first side of the engine. The lubricant insertion ports communicate with a source of lubricant. The second lubricant insertion port opens into the second crankcase chamber in a direction substantially opposite the swirling flow. The source of lubricant is regulated by a control mechanism so that each lubricant insertion port delivers about 20-55 cc/hr of lubricant during engine idle.
Another aspect of the present invention involves an internal combustion engine comprising a first cylinder formed in a first cylinder bank and a second cylinder formed in a second cylinder bank. The cylinder banks are oriented in a V-shaped formation with the first cylinder bank being generally on a first side of the engine and the second cylinder bank being generally on a second side of the engine. A crankcase encloses at least a portion of a crankshaft therein and is divided into at least a first crankcase chamber communicating with the first cylinder and a second crankcase chamber communicating with the second cylinder. A first lubricant insertion port opens into the first crankcase chamber from the second side of the engine, and a second lubricant insertion port opens into the second crankcase chamber from the first side of the engine.
A still further aspect of the present invention involves an internal combustion engine comprising at least one variable volume combustion chamber defined by at least a pair of components that move relative to each other. A crankcase at least partially encloses a crankshaft therein and has an air guide. The air guide communicates with an air inlet device and is adapted to conduct a flow of air into the crankcase. The crankshaft communicates with one of the combustion chamber components and is adapted to rotate in a manner creating a swirling flow of air within the crankcase. A lubricant insertion port communicates with a source of lubricant and opens into the crankcase in a direction substantially opposite the swirling flow.
In accordance with a still further aspect of the present invention, an internal combustion engine has at least one variable volume combustion chamber defined by at least a pair of components that move relative to each other. A fuel injector communicates with the combustion chamber and is adapted to direct a flow of fuel into the combustion chamber. A crankcase encloses a crankshaft therein and has an air guide. The air guide communicates with an air inlet device and is adapted to conduct a flow of air into the crankcase. The crankshaft is connected to one of the combustion chamber components and is adapted to rotate in a first rotation direction. A scavenge system is adapted to supply air from the crankcase to the combustion chamber. A lubricant supply system comprises an insertion port and a control mechanism. The insertion port communicates with a source of lubricant and is adapted to conduct a flow of lubricant into the crankcase. The control mechanism is adapted to regulate the volume flow of lubricant so that, during engine idle, about 20-55 cc/hr of lubricant is delivered to the crankcase.
Another aspect of the present invention also includes an internal combustion engine having at least one variable volume combustion chamber defined by at least a pair of components that move relative to each other. A fuel injector communicates with the combustion chamber and directs a flow of fuel into the combustion chamber. A. crankcase encloses a crankshaft therein and has an air guide which communicates with an air inlet device and is adapted to conduct a flow of air into the crankcase. The crankshaft is connected to one of the combustion chamber components and rotates in a first rotation direction. A scavenge system supplies air from the crankcase to the combustion chamber. A lubricant supply system comprises an insertion port and a control mechanism. The insertion port communicates with a source of lubricant and conducts a flow of lubricant into the crankcase. The control mechanism regulates the volume flow of lubricant during engine idle between a first delivery rate and a second delivery rate. The first delivery rate is selected to supply a sufficient volume of lubricant to inhibit carbonization of the lubricant, and the second delivery rate is selected to supply a small enough volume of lubricant so that lubricant resistance to crankshaft rotation will not hinder engine start.
An additional aspect of the present invention includes a method of assembling an internal combustion engine. The method includes providing a crankcase comprising a rotatable crankshaft, providing a lubricant pump, providing a source of lubricant, placing the pump in communication with the source of lubricant, placing the pump into communication through a hose with a lubricant insertion port, the port being adapted to communicate lubricant to the crankcase, driving the pump to at least partially fill the hose with lubricant, and then connecting the pump to a mechanical drive device.
The above-discussed aspects of the invention are particularly well suited with engines operating on a crankcase compression, two-cycle combustion principle; however, many of the disclosed aspects of the invention can also be used with engine types that operate on other combustion principles.
For purposes of summarizing the invention and the advantages achieved over the prior art, certain objects and advantages of the invention have been described herein above. Of course, it is to be understood that not necessarily all such objects or advantages may be achieved in accordance with any particular embodiment of the invention. Thus, those skilled in the art will recognize that the invention may be embodied or carried out in a manner that achieves or optimizes one advantage or group of advantages as taught herein without necessarily achieving other objects or advantages as may be taught or suggested herein.
All of these aspects and features are intended to be within the scope of the invention herein disclosed. These and other aspects, features and advantages of the present invention will become readily apparent to those skilled in the art from the following detailed description of the preferred embodiment having reference to the attached figures, the invention not being limited to the particular preferred embodiment disclosed.